The invention is based on a leveling system for vehicles.
Such leveling systems serve the purpose of active control of the chassis, and primarily of the wheel suspension of a vehicle, in order to suppress positional changes of the vehicle body and absorb impacts, and thus attain a comfortable, stable vehicle performance.
As in a known leveling system type referred to at the outset (German Patent Disclosure Document 39 10 030 Al), the proportional pressure regulating valve is triggered by an electric control unit for this purpose. The control unit communicates with a number of vehicle height meters, which are associated with the various wheel suspensions and sample the relative height of the vehicle body with reference to the wheel supports. Acceleration sensors for transverse and longitudinal acceleration of the vehicle are also provided, which furnish parameters that characterize the driving situation to the control unit. From the sensor signals, the control unit executes a suspension control for suppressing vehicle body roll, rocking and bounce. To this end, the pressures in the hydraulic work cylinders or actuators, disposed between the wheel suspensions and the vehicle body, are adjusted accordingly by suitable triggering of the pressure regulating valves associated with the various actuators.
When the known leveling systems are put into operation, which takes place upon vehicle starting, abrupt changes in position of the vehicle body can occur, particularly if the vehicle has been parked for a long time or if one of the sensors is defective.